TBM tunnel clearance displacement monitoring system

The utility model discloses a displacement monitoring system of a TBM tunnel clearance, which comprises embedding bars of an embedded part, a point measuring component, a target device and a laser source; three embedding bars of the embedded part are respectively fixed on rock surfaces clung to the tail arch crown of a shield of a cutter head of a development machine and the positions with maximum span at two side walls; the rear part of the point measuring component is fixed on the end head of the embedding bar of the embedded part in a sheathing way, the front end of the point measuring component is fixed in a centering way with the target device and is detachable, the laser source is mounted on a stable sector of not less than 5 times of tunnel diameter at the rear of the point measuring component and is collimated with the target device; the target device consists of a target drone, a measuring module and a sliding scale, wherein, the target drone is arranged at the upper part and the measuring module is